Chain saw link



June 16, 1953 E. -r. DUNNINGTON 2,642,102

CHAIN SAW LINK Filed June 3, 1952 uvwszvrox zjlwrraulv/mmlmg n rramvs xs.

Patented June 16, 1953 j UNITED STATES PATENT OFFICE 1 w I 2,642,162 V CHAIN SAW LINK Edwin 'I'. Dunnington, Indianapolis, Ind. Application June a, 1952, Serial No. 291 ,446-

I 1 Thisinvention relates to chain saws and more particularly to means tive life of the'saw.

As commonly constructed, the chain of a chain saw comprises side plates which interconnect, or form parts of means interconnecting, adjacent teeth-bearing links of the chain and which bear on the face of a cutter bar to transmit thereto the thrusts resulting from reaction of the work on the cutting teeth. In some classes of work. notably situations in which the chain is used In cutting floating logs and consequently runs in water, the side plates develop a tendency to crack at the pitch holes, thus rendering the side plates incapable of sustaining the longitudinal stresses impressed upon them and causing the chain to break.

It is an object of this invention to overcome or counteract this tendency of side plates to split under certain conditions encountered in chain saw operation.

I believe that the above noted tendency of side plates to split arises from work-hardening of those portions of the side plates through which lateral thrust is transmitted to the cutter bar. It seems possible that as a result of such workhardening the hardened portions of the links possess a different coefiicient of thermal expansion from that of other portions of the side plates; and that the cracks develop as a result of differential expansion when the temperature of the side plates increases due to the friction to which they are subjected. In any event, I find that the development of cracks to an extent sufficient to cause side-plate failure can be prevented by interrupting the longitudinal continuity of the sideplate faces which bear on the cutter bar or by so constructing the side plates that any cracks which do develop at their hearing faces are-prevented from reaching the pitch holes receiving the pins by which adjacent links of the chain are interconnected.

The accompanying drawing illustrates the mvention:

Fig. l is a fragmental longitudinal section chain of Fig. 1;

Fig. 3 is an elevation of a modified form .of side plate; 7

Fig. 4 is a view similar to Figs. 2 and 3 illustrating a further modification.

As indicated in Fig. l. a chain saw commonly 4 Claims. (01. ria 135) for increasing the effec includes teeth-bearing links i ll interconnected by other links at least some of which include side plates ll In operation, the chain runs along one provide an extended bearing face I5 engageable with the cutter bar to transmit the thrusts previously mentioned. As noted, cracks developing at the surfaces l5 due to conditions encountered in use tend to extend themselves until they reach the pitch holes l6 receiving the pins I! through which adjacent chain links are interconnected. When a crack occurs and extends itself to meet a pin hole, the side plate is greatly weakened and will eventually fail, causing a breaking of the chain.

In the side plate shown in Fig. 2, I have interrupted the continuity of each bearing face by providing it, opposite each associated pitch hole It, with a notch I1. Such a notch serves to reduce the extent, longitudinally of the chain, of those side-plate portions which would be subjected to internal strain as the result of differential thermal expansion. As a result, the notches tend to prevent, and are found in practice to' be effective in preventing, the start of cracks in the side plates.

In the modified form of side plates shown in Fig. 3, the plate is provided inwardly from the bearing surface l5 with a slot l8 which, longitudinally of theside plate, is substantially coextensive with the adjacent pitch-hole it. In fact, the length of the slot I8 may be slightly greater than the diameter of the pitch hole. With the slots l8 present in the side plate, any crack which develops at a bearing face I5 is prevented from extending itself to reach the pitch hole. Such a crack, once started, may extend itself inwardly of the link; but when it reaces the slot l8, further extension is prevented.

In the arrangement illustrated in Fig. 4, the side plate embodies both the features illustrated in Figs. 2 and 3. The side plate shown in Fig. 4 is provided opposite each pitch hole with a T- shaped slot [0. The shank or transversely extending portion of each such T-shaped slot opens into the bearing face l5 and corresponds to the notch ii in the side plate shown in Fig. 2 while the remaining slot-portion, extending longi- 3 tudinally of the side plate ll, corresponds to the slot l8 of Fig. 3. The slot of Fig. 4 both inhibits the initial development of cracks and also prevents any cracks which do develop from extending themselves until they reach the pitch holes l6.

Chain saws incorporating chains of the type illustrated in Figs. 2, 3, and 4 have been found to be much less subject to side-plate failure, and hence possesszarmaterially longerzliferthanchain saws in whichithe 'sidesplatesaare.tnot modified by the presence of notches or slots, l1, l8, or I9.

I claim as my invention:

1. In a chain saw having a chain including links each comprising a pair of side platespro vided adjacent their ends withlal nediholes'receiving transverse pins pivotally connectingcsaid side plates to adjacent chain links; a cutter bar; said side plates having at their GdgBSTTQPDOSitB said holes bearing faces engaging said cutter bar, each side plate having, betweeneachhole andthe adjacent. bearing. face anropen ng-lspaeed from 5 9 1110 6- 2. The invention set forth in claim 1 with the addition that said opening opens into the adjacent bearing face to interrupt the longitudinal continuity thereof.

3. The invention set forth in claim 1 with the addition that said opening is spaced inwardly from the bearing face and is substantially longitudinally coextensive with the hole.

4. The invention set forth in claim 1 with the additiomthat each vo1 said mienings :is"T'-'-3haped, .havingn transversely extending portion opening into the bearing face and a longitudinally extctending portion spaced inwardly from the hearing face.

EDWIN T. DUNNINGTON.

0 Number Name Date 3,508,784 Cox Q. :Mayl23, 1-950 2,558,678 .wGarrett June 26,1951

2,602,344 Brenner calmly 8, 1952 

